1. Field of the Invention
Embodiments of the present invention relate to multi-colorant rendering and printing. In particular, the embodiments of the present invention relate to systems and methods for limiting total colorant in a printing device or color rendering system using multidimensional simplicial subdivision and barycentric interpolation.
2. Background and Related Art
Current color printing technologies available to consumers include color printers that use various color combinations to reproduce any of a variety of colors. One such example is a color ink jet printer that propels droplets of ink directly onto paper. Low-end ink jet printers typically employ three ink colors (cyan, magenta and yellow) (CMY) to form the various color combinations to reproduce a variety of colors. For example, three-color ink jet printers produce a composite black. Four-color ink jet printers use cyan, magenta, yellow and black (CMYK). Other types of printers include laser or electrophotographic printers, dye sublimation, and other printer types that may also use CMY or CMYK colorant schemes. Certain printers or color rendering devices may use more than three or four colorant colors.
A variety of different kinds of paper, media, or other substrates may be used in association with many printers. However, each type of paper includes characteristics that affect the printing on the particular media. For example, certain clay-coated and other specialty papers can greatly improve the printed results when compared to regular copy paper because the clay-coated or other specialty paper does not absorb the ink in the same fashion as the regular copy paper.
While a wide variety of printers are available for use, problems still exist. The printing of a color image typically includes applying a number of colorants to the paper or output media. The color that is produced on the output media is dependent on the amount of each colorant that is applied to the output media. The amount of a colorant can be expressed as a percentage of up to a maximum amount of colorant that could be deposited by a deposition apparatus. Each color of colorant can be deposited up to 100%. The total amount of colorant applied to a given region of an output medium is the combined amounts of each color of colorant deposited on the region.
For example, in a four-colorant printing system, a color can be expressed as a percentage of the maximum cyan, magenta, yellow and black colorants. In such a system, theoretically, up to 400% of colorant (up to 100% of each color colorant) may be deposited on a selected region.
However, the output media typically includes a total area coverage (TAC) limit, sometimes informally referred to as the ink limit (even when the colorants are not inks per se), for the applied colorant. The TAC limit represents the maximum total amount of colorant that can be applied to a given area of the output media up to a saturation level. Such limits may be dependent on the type of media used for printing, such as the type of paper. TAC limits are generally established to avoid “failure modes” of physical print processes. Thus, if the total color combination exceeds the TAC limit the media may be over-inked, which may cause mechanical problems, image quality problems, drying problems, etc. For electrophotographic printers that use CMYK colorants, for example, a TAC limit might be set at 280% while the maximum allowable amount for any single colorant might be 100%. If the total amount of applied colorant in such a system exceeds 280%, the toners might not reliably adhere to the paper, print quality may be adversely affected, and/or the printer mechanisms might become contaminated by excess unfused toner.
Therefore, in developing printer firmware, print drivers, color profiling software, color management modules (CMMs) and the like, it is necessary to implement measures to ensure that the TAC limit appropriate for the print process (including substrate, paper, or other media) is not exceeded. Conventional methods of colorant limitation have significant problems. These conventional methods include clipping out-of-limit values onto the limit and scaling the individual printing colorants. Clipping out-of-limit values, however, is not invertible, and scaling individual printing colorants does not utilize the entire colorant-limited gamut of colors.